. This application requests continued support for the final five years of a randomized trial of BSE currently being conducted in 435 factories of the Shanghai Textile Industry Bureau. The purpose of the study is to determine whether the regular practice of BSE will reduce mortality from breast cancer. Over 267,000 current and retired female workers between the ages of 30 and 64 in 1989 were randomized by factory to an intervention or control group. Women in the intervention group received initial BSE instruction in 1989-91, reinforcement sessions in 1991-92 and 1993-95, and multiple interim reminders to practice BSE, and had their BSE supervised by a medical worker twice a year. All women are being actively followed for vital status and residence in Shanghai, and multiple active and passive methods are utilized to identify all incident and fatal breast cancers. High levels of compliance and competency in practicing BSE for the first five years of the trial have been documented, as has the capacity to track a high proportion of women in the study and identify virtually all breast cancer deaths. As anticipated from results of mammography trials, breast cancer mortality rates through year 4 of follow-up (1994) were similar in the two study arms, and follow-up for 10 years (through the year 2000), as originally anticipated, will be necessary, and is proposed in this renewal application. No further intervention activities are proposed. After 10 years of follow-up, over 2.6 million woman-years will have accrued, and this trial will have 80% power to detect a reduction in breast cancer mortality of 30%.